python变量不能以数字打头详解

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在编写python函数时，无意中发现一个问题：python中的变量不能以数字打头，以下函数中定义了一个变量3_num_varchar，执行时报错。

函数如下：

def database_feild_varchar_trans(in_feild): ''' transfer the feild if varchar then 3times lang else no transfer ''' feild_split = in_feild.split(' ') is_varchar = feild_split[1].find('VARCHAR') if is_varchar >= 0 : num_varchar = feild_split[1].replace('VARCHAR','').replace('(','').replace(')','') print (num_varchar) 3_num_varchar = num_varchar*3 feild_split[1] = feild_split[1].replace(str(num_varchar),str(3_num_varchar)) return feild_split else: print ('The feild type is not varchar') return feild_split

报错信息如下：

>>> runfile('E:/procedure/python/projects/others/table_test.py', wdir='E:/procedure/python/projects/others') Traceback (most recent call last): File "", line 1, in File "D:python33libsite-packagesspyderlibwidgetsexternalshellsitecustomize.py", line 699, in runfile execfile(filename, namespace) File "D:python33libsite-packagesspyderlibwidgetsexternalshellsitecustomize.py", line 88, in execfile exec(compile(open(filename, 'rb').read(), filename, 'exec'), namespace) File "E:/procedure/python/projects/others/table_test.py", line 20 3_num_varchar = int(num_varchar)*3 ^ SyntaxError: invalid Syntax 将变量3_num_varchar改为num_varchar_3，运行成功，程序改为如下： import os import sys str1='aaa varchar(10)' def database_feild_varchar_trans(in_feild): ''' transfer the feild if varchar then 3times lang else no transfer ''' feild_split = in_feild.split(' ') is_varchar = feild_split[1].find('VARCHAR') if is_varchar >= 0 : num_varchar = feild_split[1].replace('VARCHAR','').replace('(','').replace(')','') print (num_varchar) num_varchar_3 = num_varchar*3 feild_split[1] = feild_split[1].replace(str(num_varchar),str(num_varchar_3)) return feild_split else: print ('The feild type is not varchar') return feild_split print (database_feild_varchar_trans(str1))

运行结果：

>>> runfile('E:/procedure/python/projects/others/table_test.py', wdir='E:/procedure/python/projects/others') The feild type is not varchar ['aaa', 'varchar(10)']

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